IA-32 architecture
datatypes




 
integer datatype formats
 
 
signed byte
7 6..0
S integer
signed word
15 14..0
S integer
signed dword
31 30..0
S integer
 
unsigned byte
7..0
integer
unsigned word
15..0
integer
unsigned dword
31..0
integer
unsigned qword
63..0
integer
 
BCD
7..4 3..0
res. BCD
packed BCD
7..4 3..0
BCD BCD
 
 
pointer datatype formats
 
 
near pointer
31..0
offset or virtual address
far pointer
47..32 31..0
segment or selector offset
 
 
FP datatype formats
 
 
single real
31 30..23 22..0
S exp. fraction
double real
63 62..52 51..0
S exp. fraction
extended real
79 78..64 63 62..0
S exp. I fraction
 
word integer
15 14..0
S integer
short integer
31 30..0
S integer
long integer
63 62..0
S integer
 
packed BCD
79 78..72 71..0
S res. D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
 
 
MMX datatype formats
 
 
packed byte
63..56 55..48 47..40 39..32 31..24 23..16 15..8 7..0
byte byte byte byte byte byte byte byte
packed word
63..48 47..32 31..16 15..0
word word word word
packed dword
63..32 31..0
dword dword
qword
63..0
qword
packed byte
127..120 119..112 111..104 103..96 95..88 87..80 79..72 71..64 63..56 55..48 47..40 39..32 31..24 23..16 15..8 7..0
byte byte byte byte byte byte byte byte byte byte byte byte byte byte byte byte
packed word
127..112 111..96 95..80 79..64 63..48 47..32 31..16 15..0
word word word word word word word word
packed dword
127..96 95..64 63..32 31..0
dword dword dword dword
packed qword
127..64 63..0
qword qword
 
 
SSE datatype format
 
 
scalar single FP
127..96 95..64 63..32 31..0
reserved reserved reserved single FP
packed single FP
127..96 95..64 63..32 31..0
single FP single FP single FP single FP
 
 
SSE2 datatype format
 
 
scalar double FP
127..64 63..0
reserved double FP
packed double FP
127..64 63..0
double FP double FP



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